MATH question

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Discus: SAT/ACT Tests and Test Preparation: August 2003 Archive: MATH question
 By Akaflex (Akaflex) on Monday, August 25, 2003 - 01:33 pm: Edit

Chk out profile for pic

In the fig, BE parrallel to CD. If AE = 10, AD= 16, CD=8, AND AC=20, what is the perimeter of triangle ABE.

A- 25
B- 27.5
C- 28
D- 41.5
E- 32

can sum1 plz explain thorougly

 By Serene (Serene) on Monday, August 25, 2003 - 01:43 pm: Edit

Use similar triangles ABE and ACD. Figure out the other two lengths.

 By Akaflex (Akaflex) on Monday, August 25, 2003 - 01:58 pm: Edit

In Triangle ABC, the length of AC is 12 and the length of BC is 7. The area of triangle ABC is 42

Col. A

The measure of Angle C

B

90 Degrees

i need help on dis one too, thanks. Serene i did use similar triangle, i got all the sides except side BE which i couldnt get....

 By Serene (Serene) on Monday, August 25, 2003 - 02:03 pm: Edit

 By Akaflex (Akaflex) on Monday, August 25, 2003 - 02:03 pm: Edit

heres another one plz explain merci

In a certain group of 30 men, each man has either a beard , a mustache, or both. If 15 of the men have a beard and 25 of the men hae a mustache, how many of the men have only a beard?

 By Serene (Serene) on Monday, August 25, 2003 - 02:05 pm: Edit

15+25-30=10=the number of men who have both
15-10=5=number of men who have beard but not mustache

 By Serene (Serene) on Monday, August 25, 2003 - 02:06 pm: Edit

If angle C is right angle, area of ABC = 12*7/2 = 42 which is right. So A=B. Answer is C.

 By Akaflex (Akaflex) on Monday, August 25, 2003 - 02:07 pm: Edit

heres another one plz explain merci

In a certain group of 30 men, each man has either a beard , a mustache, or both. If 15 of the men have a beard and 25 of the men hae a mustache, how many of the men have only a beard?

 By Akaflex (Akaflex) on Monday, August 25, 2003 - 02:09 pm: Edit

hmm sorry for the duplicate, thanks for explanation

 By Akaflex (Akaflex) on Monday, August 25, 2003 - 02:35 pm: Edit

Heres another one, which confuses the hell out of me, it either takes to long my way or sumthin

_ 4 : 34

The face of a 12-hour digital clock, pictured above, shows one example of a time at which reading the digits from left to right is the same as reading the digits from right to left. How many such times would be shown on this clock in a 12-hour period starting at 12 midnight?

 By Akaflex (Akaflex) on Monday, August 25, 2003 - 02:40 pm: Edit

Heres another one, which confuses the hell out of me, it either takes to long my way or sumthin

_ 4 : 34

The face of a 12-hour digital clock, pictured above, shows one example of a time at which reading the digits from left to right is the same as reading the digits from right to left. How many such times would be shown on this clock in a 12-hour period starting at 12 midnight?

 By Xiggi (Xiggi) on Monday, August 25, 2003 - 02:56 pm: Edit

I would say 62.

 By Serene (Serene) on Monday, August 25, 2003 - 03:06 pm: Edit

how did you get 62? I got 57 i think...

 By Madrigal (Madrigal) on Monday, August 25, 2003 - 03:09 pm: Edit

Find a pattern. For 2 digit hours (12,11,10) there will be only one time that reads the same forwards and backwards (12:21, 11:11, 10:01). For 1 digit hours there will be 6 times that read the saem forward and backward (1:01, 1:11, 1:21, 1:31, 1:41, 1:51)
Therefore
1AM and 1PM - 12 palindromes
2AM and 2PM - 12 palindormes
3AM and 3PM - 12 palindromes
4AM and 4PM - 12 palindromes
5AM and 5PM - 12 palindromes
6AM and 6PM - 12 palindromes
7AM and 7PM - 12 palindromes
8AM and 8PM - 12 palindromes
9AM and 9PM - 12 palindromes
10AM and 10PM - 2 palindromes
11AM and 11PM - 2 palindromes
12AM and 12PM - 2 palindromes

Now it may be helpful to list them like this, it is not the quickest method. I would have probably done it like this. 1 digit hours have 6 palindromes, there are 9 1 digit hours in a 12 hour cycle. 9*6 = 54. There are 3 2-digit hours, 3*1=3. Add those, 57 palindromes.

 By Akaflex (Akaflex) on Monday, August 25, 2003 - 03:09 pm: Edit

57 is right, but ? i still dunt get it?

 By Fairyofwind (Fairyofwind) on Monday, August 25, 2003 - 03:09 pm: Edit

1:01 1:11 ... 1:51
2:02 2:12 ... 2:52
.
.
.
9:09 9:19 ... 9:59
10:01
11:11
12:21

As Serene said, 57 in total.

 By Serene (Serene) on Monday, August 25, 2003 - 03:10 pm: Edit

First it's in 12 hour period, so AM and PM don't count twice.
And each digit hour has 6, not 5 palindromes.

 By Madrigal (Madrigal) on Monday, August 25, 2003 - 03:13 pm: Edit

note: edited already, and the double listing was to show all the possible palindromes.

 By Xiggi (Xiggi) on Monday, August 25, 2003 - 03:23 pm: Edit

Hehe - I probably made a few incorrect asuumptions to get to 62.

1. The clock at MIDNIGHT should indicate _0:00 since the question said -4:34 and not 04:34
2. The twelve hour period terminates at 11:59

So I counted 0:10, 0:20, 0:30, 0:40, 0:50 AND 0:00

Then I added the 1:x1, and so forth. This gave me 6 times ten.

Then I added the 10:01 and 11:11 to get to to 62. I did not count 12:21 since that is after noon.

Oh well

 By Xiggi (Xiggi) on Monday, August 25, 2003 - 03:32 pm: Edit

This what it looked like on Xiggi's clock

0 0 0
0 1 0
0 2 0
0 3 0
0 4 0
0 5 0
1 0 1
1 1 1
1 2 1
1 3 1
1 4 1
1 5 1
2 0 2
2 1 2
2 2 2
2 3 2
2 4 2
2 5 2
3 0 3
3 1 3
3 2 3
3 3 3
3 4 3
3 5 3
4 0 4
4 1 4
4 2 4
4 3 4
4 4 4
4 5 4
5 0 5
5 1 5
5 2 5
5 3 5
5 4 5
5 5 5
6 0 6
6 1 6
6 2 6
6 3 6
6 4 6
6 5 6
7 0 7
7 1 7
7 2 7
7 3 7
7 4 7
7 5 7
8 0 8
8 1 8
8 2 8
8 3 8
8 4 8
8 5 8
9 0 9
9 1 9
9 2 9
9 3 9
9 4 9
9 5 9
1 0 0 1
1 1 1 1

 By Fairyofwind (Fairyofwind) on Monday, August 25, 2003 - 03:33 pm: Edit

Whoa.

 By Madrigal (Madrigal) on Monday, August 25, 2003 - 03:37 pm: Edit

Only 24-hour clocks shouw 0:00 at midnight, but that is what my watch looks like. If I had done the problem by watching my watch (heh heh) and counting the palindromes, I would have had the same answer you did :-).

 By Xiggi (Xiggi) on Monday, August 25, 2003 - 03:42 pm: Edit

The question said a 12-hours digital ... so I was wrong. We do not have too many digital 12 hours clock in my home. I guess it is part of the European heritage. Thank God, we do not have cuckoos

 By Madrigal (Madrigal) on Monday, August 25, 2003 - 03:45 pm: Edit

Haha. Cuckoo clocks = awesome